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Wednesday, March 20, 2013

Are Cottonmouths Aggressive?

A
few years ago I was walking alongside the edge of pond in the Florida panhandle
when I was startled by some splashing noises in the water. I had accidentally
gotten too close to a Cottonmouth (Agkistrodon
piscivorus) and the snake was warning me away by vibrating its tail in the
water and flashing its white mouth. It was obvious to me that the snake thought
I was getting too close and it was warning me away before things got serious.
Neither of us wanted to be involved in a venomous snakebite.

I’ve
heard stories about aggressive Cottonmouths so many times that they are hard to
discount. But I believe, as with so many other Cottonmouth myths, that normal
snake behavior is being misinterpreted. For one thing, a Cottonmouth has
nothing to gain by being aggressive towards large potential predators like
people. In any case, after hearing this story one too many times, a couple
researchers in South Carolina decided to test just how a Cottonmouth reacted
when confronted by a human. In their words, “We examined defensive behavior of wild cottonmouths in response to a
human aggressor by subjecting them to one or more of three different
treatments. When we encountered a cottonmouth in the field, we approached the
snake and either (1) stood beside it with a "snakeproof" boot
touching its body, (2) stepped on the snake at midbody with enough force to restrain
but not injure it, or (3) picked up the snake at midbody with a pair of 1-m
snake tongs (Whitney Tongs) with a grasping handle that was modified to
resemble a human arm and hand. A leather glove was fitted over the end of the
tongs, with one extension covered by the thumb and the other by the middle
finger. Hence, the glove could be closed around the snake's body. A padded
shirt sleeve was used to cover the remainder of the rod up to the handle. Each
treatment was carried out for 20 sec, and the behavior of each snake was
recorded.”

In
other words, they walked up to Cottonmouths, stepped on Cottonmouths, and
picked up Cottonmouths with fake arms and watched what happened. Who said
science wasn’t entertaining? They ended up standing alongside 13, stepping on
22, and picking up 36 snakes. None of the snakes they stood beside tried to
bite, one of the snakes they stepped on bit them and just 13 (36%) of the
picked-up snakes bit the fake arm. Overall, most snakes either tried to escape
or gave defensive displays to scare off the people without trying to bite. There
are two primary lessons here: Cottonmouths aren’t eager to bite even when they
are harassed and you shouldn’t try to pick up Cottonmouths (although if you are
inclined to pick up venomous snakes then a scientific paper may not be enough
to convince you to do otherwise).

So
what about all these stories of Cottonmouths chasing people? I have long argued
that when a Cottonmouth is scared it will head right for the water and if you
are in between the Cottonmouth and where that Cottonmouth wants to go, it will
come right at you. Again, we can go to the scientific literature to find an
experiment on the subject. A study was undertaken in Florida to evaluate how
Cottonmouths behaved after you A) scared them into trying to escape and then B)
stepped in front of them. As you might expect, the Cottonmouths were pissed
off! From the study, Cottonmouths, “…exhibited several characteristic behaviors,
including crawling rapidly toward me, raising the head and neck off the ground,
expanding the jaws, flattening the body, vibrating the tail, tongue-flicking,
lunging and striking forward, and rarely, musk-squirting. A great deal of
variation exists in the intensity of these behaviors.”

What’s
the lesson here? When you see a Cottonmouth that looks like it is going
somewhere…Let it go.

The
author concludes, “I believe that the, “...'aggressive bluffing' behavior I have
witnessed…were elicited under the special circumstances of encountering the
snakes in habitats familiar to them and by blocking their escape along a
direction they had chosen.”